1. Field of the Invention
The present invention relates to a display element, particularly an electroluminescent display element and a process for producing the same.
2. Background Art
An electroluminescent display element, especially an electroluminescent element (hereinafter often referred to as “EL element”), basically comprises a transparent substrate and, stacked on the transparent substrate in the following order, an anode, a luminescent layer, and a cathode and is constructed so that luminescence in the EL element occurs from the anode side (substrate side).
In order to cope with demands for diversification of screen display devices and the like, however, EL elements, which cause luminescence from the cathode side, have been required and developed. For example, Japanese Patent Laid-Open No. 43980/2001 proposes a cathode luminescence-type organic EL element in which an anode in its part in contact with an organic layer side contains a metal belonging to the group 5 or 6 of the periodic table (particularly chromium, molybdenum, tangsten, tantalum, and niobium) which can inhibit the occurrence of dark spots (nonluminous points) and thus can prevent uneven luminescence. Japanese Patent Laid-Open No. 216976/2002 proposes an organic EL element which can make the roughness of the surface of the lower electrode even and can suppress the occurrence of a leak current and dark spots by virtue of the adoption of a lower electrode comprising a metal layer (chromium) and a buffer thin-film layer formed by sputtering an oxide of the metal having a higher electrical conductivity than an organic layer on the metal layer.
At the present time, however, there remains an earnest desire for the development of a display element which has been improved in current density and luminescence efficiency over an indium-tin oxide (ITO) electrode.